One type of a conventional ion laser comprises an AC power source having an output voltage of, for instance, 100 V, an auto-transformer for stepping the output voltage up to, for instance, 115 V to 120 V, a rectifying circuit for rectifying the AC power of the AC stepped-up voltage to DC power, a capacitor for smoothing the DC power to produce a DC power having less ripple, a starter circuit for producing a high voltage pulse to be applied to an ion laser tube, a choke coil avoiding the application of the high voltage pulse to the rectifying circuit, a low voltage portion of the starter circuit etc., and a power transistor path bank for controlling the discharge current of the ion laser tube.
In operation, AC power is supplied from the AC power source, and the voltage of the AC power is stepped up from 100 V to, for instance, 120 V by the auto-transformer. Then, the AC power is rectified to provide DC power. The DC power is smoothed to provide DC power having less ripple by the smoothing capacitor. Thus, the smoothed DC power is supplied to the starter circuit, and also supplied through the choke coil to the on laser tube. Assuming that the discharge starting voltage of the ion laser tube is 2 KV, a high voltage impulse of, for instance, 3 KV is produced in the starter circuit. The high voltage impulse is applied across an anode and a cathode of the ion laser tube from the starter circuit which starts operating by receiving the stepped-up DC voltage, so that the ion laser tube is driven to discharge, while the high voltage impulse is not applied to the low voltage portion of the starter circuit, the rectifying circuit etc. in the presence of the choke coil. Thus, the ion laser tube continues to discharge by receiving the smoothed DC power. In this circumstance, the discharge current and the discharge voltage of the ion laser tube are, for instance, 8 A (usually ranging 5 A to 12 A), and 90 V, respectively. Therefore, the whole DC power is not consumed in the ion laser tube, and the surplus DC power is consumed in the power transistor path bank.
In the conventional ion laser, however, there is a disadvantage that the auto-transformer is of a large power capacity, thereby being large in size and heavy in weight, because the discharge of the ion laser tube is a large current.
There is further disadvantage that a power efficiency is decreased, because the surplus power is consumed in the poewr transistor path bank, thereby radiating heat therefrom.